Basic Study on the Seismic Response of the High-Speed Rotational Body Supported by Fluid Film Bearings

2011 ◽  
Author(s):  
Masayoshi Hatta ◽  
Atsuhiko Shintani ◽  
Tomohiro Ito
Keyword(s):  
High Speed ◽  
Seismic Waves ◽  
Equations Of Motion ◽  
Rotating Disk ◽  
Fluid Film ◽  
Basic Study ◽  
Fluid Forces ◽  
Shaft System ◽  
Fluid Film Bearings ◽  
Response Behaviors

In this study, the seismic responses of a disk and a shaft are evaluated analytically. In an analytical model, the disk-shaft system is treated as an elastic shaft with a rigid disk, and the shaft is supported by fluid film bearings. Furthermore, the gyroscopic effect of a disk and the fluid forces due to fluid film bearings are considered. The equations of motion are derived for the translational and rotational motions when the floor is subjected to horizontal and vertical excitations. The displacements of the centers of the disk and the shaft are evaluated by numerical simulations. At first, the response behaviors of a rotating disk without base excitation are evaluated, and at second, the effects of sinusoidal base excitations are investigated. Finally, the response behaviors of this system are subjected to seismic waves of varying frequencies. The results of the different seismic wave input are studied.

Study on the Seismic Response of High-Speed Rotational Disk-Shaft System

2012 ◽  
Author(s):  
Tomohiro Ito ◽  
Masayoshi Hatta ◽  
Atsuhiko Shintani ◽  
Chihiro Nakagawa
Keyword(s):  
Seismic Response ◽  
Seismic Wave ◽  
High Speed ◽  
Equations Of Motion ◽  
Rotating Disk ◽  
Seismic Responses ◽  
Shaft System ◽  
High Speed Rotation ◽  
Gyroscopic Effects ◽  
Response Behaviors

Recently, huge earthquakes occurred in the world, such as Great East Japan Earthquake in Japan or huge earthquake in New Zealand in 2011. In Niigata-ken Chuetsuoki earthquake in 2007, turbine blade collisions with the casing were found. Therefore, it is very important to clarify the seismic response behaviors of the high-speed rotational shaft like turbine shafts, because high-speed rotation will cause characteristic dynamic effects, such as gyro moment. In this study, seismic responses of a disk-shaft system are evaluated analytically. The disk-shaft system is treated as an elastic shaft with a rigid disk. In this analysis, gyroscopic effects of a rotating disk are also considered. Equations of motion are derived for the translational and rotational motions when the system is subjected to both horizontal and vertical seismic excitations. Response behaviors of a rotating disk-shaft system are evaluated for sinusoidal excitations and seismic wave excitations. In the sinusoidal excitations, excitation frequencies and rotational speed are varied, and in the seismic wave excitations, seismic responses are evaluated for the waves with various predominant frequencies.

scholarly journals Improvement of Tilting-Pad Journal Bearing Operating Characteristics by Application of Eddy Grooves

Lubricants ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 18
Author(s):  
Eckhard Schüler ◽  
Olaf Berner
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Load Capacity ◽  
Fluid Film ◽  
Operating Characteristics ◽  
Fluid Film Bearings ◽  
Tilting Pad ◽  
Bearing Load ◽  
Bearing Loads ◽  
Tilting Pad Journal Bearing

In high speed, high load fluid-film bearings, the laminar-turbulent flow transition can lead to a considerable reduction of the maximum bearing temperatures, due to a homogenization of the fluid-film temperature in radial direction. Since this phenomenon only occurs significantly in large bearings or at very high sliding speeds, means to achieve the effect at lower speeds have been investigated in the past. This paper shows an experimental investigation of this effect and how it can be used for smaller bearings by optimized eddy grooves, machined into the bearing surface. The investigations were carried out on a Miba journal bearing test rig with Ø120 mm shaft diameter at speeds between 50 m/s–110 m/s and at specific bearing loads up to 4.0 MPa. To investigate the potential of this technology, additional temperature probes were installed at the crucial position directly in the sliding surface of an up-to-date tilting pad journal bearing. The results show that the achieved surface temperature reduction with the optimized eddy grooves is significant and represents a considerable enhancement of bearing load capacity. This increase in performance opens new options for the design of bearings and related turbomachinery applications.

Optimum Design of Fluid Film Bearing for HDD Spindle Considering the Tolerances

2010 ◽  
Author(s):  
Yuta Sunami ◽  
Masayuki Ochiai ◽  
Hiromu Hashimoto
Keyword(s):  
Optimum Design ◽  
High Speed ◽  
Low Noise ◽  
Production Costs ◽  
Fluid Film ◽  
Rotating Shaft ◽  
Fluid Film Bearings ◽  
Support Element ◽  
Characteristic Values ◽  
Bearing Characteristic

Fluid film bearings are widely used for high speed rotating machineries acting as rotating shaft support element. Especially, the bearings are widely applied to the OA equipments and IT devices. Optimization of bearing parameters is effective to improve the performance of the fluid film bearings since low noise and impact-proof characteristics are essential requirements for these equipments. On the other hand, bearings for miniaturized spindles are generally made by mass production process which will eventually requires reduction of production costs. In this paper, therefore small size HDD spindle using fluid film bearings is treated. Sensitivity analysis and optimum design that considered dimensional tolerances using the probabilistic techniques are conducted. As a result, the influence of bearing characteristic values on the occurrence of dimensional tolerances was clarified.

Basic Study on the Seismic Response of the High-Speed-Moving Vehicle Considering Passengers' Dynamics

2012 ◽  
Vol 452-453 ◽  
pp. 1200-1204
Author(s):  
Atsuhiko Shintani ◽  
Tomohiro Ito ◽  
Yudai Iwasaki
Keyword(s):  
High Speed ◽  
Equations Of Motion ◽  
Seismic Excitations ◽  
Lagrangian Equation ◽  
Basic Study ◽  
Moving Vehicle ◽  
Seismic Input ◽  
The Stability ◽  
Risk Rate ◽  
Two Degree Of Freedom

The stability of the high-speed running vehicle subjected to seismic excitations considering passengers' dynamics are considered. A vehicle consists of one body, two trucks and four wheel sets. A passenger is modeled by simple two degree of freedom vibration system. The equations of motion of the vehicle and passengers are calculated by Lagrangian equation of motion. Combining two models, the behavior of the vehicle subjected to actual seismic input considering passengers' dynamics are calculated by numerical simulation. The stability of the vehicle is evaluated by using the risk rate of rollover. We investigate the possibility of the rollover of the vehicle. We focus on the effect of the dynamic characteristics of the human and the number of the passengers when the vehicle is subjected to the seismic excitation.

Diesel Engine Turbocharger Stabilized With Novel Tilting Pad Bearing Design

2012 ◽  
Author(s):  
R. Gordon Kirk ◽  
Matthew Enniss ◽  
Daniel Freeman ◽  
Andrew Brethwaite
Keyword(s):  
High Speed ◽  
Fluid Film ◽  
Pressure Pulsations ◽  
The Past ◽  
Fluid Film Bearings ◽  
Film Instability ◽  
Tilting Pad ◽  
Full Speed ◽  
Bearing Design ◽  
Engine Testing

Many high speed turbochargers operate with limit cycle vibration as a result of fluid-film instability. This problem has been under investigation for the past seven years. Only now has a turbocharger with fluid film bearings been run to full speed and loaded, with essentially no bearing induced sub-synchronous vibration. The goal of this research was to have a stable synchronous response with a minimum of non-synchronous contribution excited only by the engine dynamics and exhaust pressure pulsations. Previous papers have documented experimental results of the fixed geometry bearing designs. This paper documents a new, modified tilting pad bearing concept that has replaced the fixed geometry bushings with minimal modifications to the stock bearing housing. The summary of the on-engine testing over the past year is documented in this paper.

Oil Whip Whirl Orbits of a Rotor in Sleeve Bearings

1967 ◽  
Vol 89 (4) ◽  
pp. 813-823 ◽  
Author(s):  
J. W. Lund ◽  
E. Saibel
Keyword(s):  
Nonlinear Equations ◽  
Limit Cycles ◽  
Equations Of Motion ◽  
The Self ◽  
Static Equilibrium ◽  
Fluid Film ◽  
Graphical Form ◽  
Method Of Averaging ◽  
Oil Whip ◽  
Fluid Film Bearings

An analysis of the self-excited oscillations, known as “oil whip,” of a rotor supported in fluid film bearings is presented. The source of the instability is the hydrodynamic forces of the bearing fluid film. The equations of motion are nonlinear, and they are studied to determine the limit cycles of the system, also called the whirl orbits. The nonlinear equations are solved by the method of averaging whereby the whirl orbits are obtained directly. The results are dimensionless and are given in graphical form. They show under which conditions whirl orbits can exist, and the position and the size of the orbits are also given. It is found that the orbits are only encountered in a relatively narrow speed interval around the speed at which the static equilibrium becomes unstable.

Effects of Turbulence and Viscosity Variation on the Dynamic Coefficients of Fluid Film Journal Bearings

1985 ◽  
Vol 107 (2) ◽  
pp. 256-261 ◽  
Author(s):  
D. F. Wilcock ◽  
O. Pinkus
Keyword(s):  
High Speed ◽  
Dynamic Stiffness ◽  
Journal Bearings ◽  
Fluid Film ◽  
Turbulent Regime ◽  
Dynamic Coefficients ◽  
Damping Characteristics ◽  
Fluid Film Bearings ◽  
Viscosity Variation ◽  
Stiffness And Damping

Many high-speed or large fluid film bearings operate in the turbulent regime. However, relatively little consideration has been given to the effects of turbulence and of the variation in viscosity on the dynamic stiffness and damping characteristics of the bearings. Since the dynamic behavior of the rotor supported on such bearings is often closely tied to the bearing dynamic coefficients, knowledge of them may be critical to both the design and the in-place correction of rotor instabilities. These effects are here considered in some detail on the basis of computer calculated analytical results, both in general dimensionless terms and with regard to a specific numerical example.

Parametric resonances for torsional vibration of excited rotating machineries with nonconstant velocity joints

2017 ◽  
Vol 24 (15) ◽  
pp. 3262-3277 ◽  
Author(s):  
Masoud SoltanRezaee ◽  
Mohammad-Reza Ghazavi ◽  
Asghar Najafi
Keyword(s):  
Torsional Vibration ◽  
High Speed ◽  
Power Transmission ◽  
Equations Of Motion ◽  
Monodromy Matrix ◽  
Parametric Instability ◽  
Constant Input ◽  
Inertia Moment ◽  
Disk Model ◽  
Shaft System

The shaft system is a rotating machinery with many applications due to its high speed. The angle between shafts may not be zero. So the shafts can be connected to each other through a nonconstant velocity U-joint, which transforms a constant input angular velocity into a periodically fluctuating velocity. Consequently, the mechanism is parametrically excited and may face resonance conditions. Herein, a power transmission system including three elastic shafts is considered. The polar inertia moment of each shaft is modeled as a dynamic system with two discrete disks at the shaft ends. The equations of motion consist of a set of Mathieu–Hill differential equations with periodic coefficients. The dynamic stability and torsional vibration of the shaft system are analyzed. The system geometry and inertia moment effect are the main issues in this contribution. Parametric instability charts are achieved via the monodromy matrix technique. The graphical numerical results are validated with the frequency analytical results. Finally, the stability regions are shown in the parameter spaces of velocity, misalignment angles and the inertia of disks. The results demonstrated that by changing the system inertia and geometry, stabilizing the whole system is possible. Moreover, to check the precision of the model, the results are compared with a basic single-disk model, which is prevalent in two-shaft systems.

Development of a High Speed Gas Bearing Test Rig to Measure Rotordynamic Force Coefficients

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
J. Jeffrey Moore ◽  
Andrew Lerche ◽  
Timothy Allison ◽  
David L. Ransom ◽  
Daniel Lubell
Keyword(s):  
High Speed ◽  
High Amplitude ◽  
Fluid Film ◽  
Test Rig ◽  
Force Coefficient ◽  
Gas Bearings ◽  
Foil Bearings ◽  
Fluid Film Bearings ◽  
Wide Range ◽  
Gas Bearing

The use of gas bearings has increased over the past several decades to include microturbines, air cycle machines, and hermetically sealed compressors and turbines. Gas bearings have many advantages over traditional bearings, such as rolling element or oil lubricated fluid film bearings, including longer life, ability to use the process fluid, no contamination of the process with lubricants, accommodating high shaft speeds, and operation over a wide range of temperatures. Unlike fluid film bearings that utilize oil, gas lubricated bearings generate very little damping from the gas itself. Therefore, successful bearing designs such as foil bearings utilize damping features on the bearing to improve the damping generated. Similar to oil bearings, gas bearing designers strive to develop gas bearings with good rotordynamic stability. Gas bearings are challenging to design, requiring a fully coupled thermo-elastic, hydrodynamic analysis including complex nonlinear mechanisms such as Coulomb friction. There is a surprisingly low amount of rotordynamic force coefficient measurement in the literature despite the need to verify the model predictions and the stability of the bearing. This paper describes the development and testing of a 60,000 rpm gas bearing test rig and presents measured stiffness and damping coefficients for a 57 mm foil type bearing. The design of the rig overcomes many challenges in making this measurement by developing a patented, high-frequency, high-amplitude shaker system, resulting in excitation over most of the subsynchronous range.

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